Rb25/30 High Oil Pressure

[PSI086]

Got a mate's new 25/30 running today but the oil pressure seems to be a lot higher than it should. Was over 100psi at cold idle. It's currently got running in oil in the engine and has 2 x1.5mm oil restrictors to the head and I'm 99% certain a RB25 oil pump. The vct has an external feed to it but isn't wired up. I'm running a 25 pump on my RB30 and its only got around 60psi at cold idle. Is there any logical reason why it would be running such high pressure?

Also the vct feed is a -4 line. Does it need a restrictor in it at all or will it not matter as we most likely won't be wiring it up so the oil will just drain back to the sump

Edited June 22, 2013 by PSI086

[KiwiRS4T]

Why would you not connect the VCT? My RB30 hits over 100psi from cold but it has an N1 pump. What kind of oil do you have in it?

[PSI086]

The oil is a Penrite running in 20/50. Going to run a 10w in it once its got a few km's on it and is ready for synthetic though. Might just see what the pressure is like with the proper oil and normal running temperature. I can't see any reason why it would be higher than a normal RB25 as everything is identical besides the lack of oil squirters under the pistons

Just got the car running with the RB20 tune which was in it previously so can't really take advantage of the vct just yet. Will most likely wire it up though. From what I understand it just needs to be activated with an rpm triggered relay?

[Simon-S14]

what oil pressure gauge and sender>?

[PSI086]

Its an autometer mechanical gauge which is identical to what's in my own car. I might try another gauge just so that can be eliminated

[luke gtr]

ive got 15/40 penrute run in oil, standard 26 pump with billet gears, 1.5 restrictor, and mine hit about 150psi on first start up.

thats with mechanical workshop gauge.

[PSI086]

If you have done a change since the run in oil whats the pressure like in yours now?

[luke gtr]

havnt done a change, but drips when it warms up and thins out.

will let you know once its run in and fresh oil.

[ScreamerNewbie]

sorry to bring up the dead guys but im going though the same drama at the moment with my rb25/30 non vct that's just being built and getting tuned

120psi on cold startup and idled at 1500 on penrite running in oil. this seems worrying!!!???? potential to blow seals etc?

im reading this from a auto meter prolite mechanical gauge.

not sure what the warm oil pressure will be just yet as I haven't let it get to that stage yet.

the oil pump is a rb25det pump with billet gears.

block has 2x 1.3mm restrictors and the vct line is disconnected.

ANY IDEAS ON A FIX??

[Piggaz]

I had 10 bar on first start up with my build on the same oil. After a a few sessions on the dyno and some road kms it came down to 7-8 bar on cold start and 3.5 warm.

How many kms has it done?

[ScreamerNewbie]

oh shit! that's high for cold start!! once warm that aint to bad! wat oil ?

at what point do we start thinking f**k that's dangerous could blow rear main and front seals etc?

hasn't done any kms, 1st startup was today and after about 10seconds I noticed it was sitting on 120psi at 1500rpm (didn't wana rev any higher plus 1st EVER start up for the engine.

[Piggaz]

The Penrite running in oil that was.

[ScreamerNewbie]

Hmmm ok, hoping its just the thicker oil n once warm ot plays nice...

[ScreamerNewbie]

hey all, find any solutions to these 25/30 high oil pressure issues??

my freshly built forged rb25/30 is showing over 100PSI on my autometer mechanical gauge, oil features include:

tomei oil pump

2X1/3mm restrictors

-12 rear head drain

2X-12 sump breathers

2X-12 cam cover breathers

grub screwed VCT feed in head

VCT sensor removed and capped

drilled out oil drains in block

2L accusump

5.5L sump

19row mocal cooler

GREX oil thermostat and oil filter relocation with ryco z145a filter

on penrite running in oil 15w40 it was showing high oil pressure over 100psi on cold start then down to 90 once warm. a tap of the revs to 2500rpm and it went to over 100psi again (gauge only goes to 100psi). after 250kms the oil was drained and a penrite 10w40racing synthetic was put in. once again on cold start over 100psi but once warm it dropped to 80/85psi or there abouts at idle and only went over 100 after 3000rpm

I was thinking of going a lighter viscosity maybe a 5w30synthetic or something? I only use penrite.

could anyone recommend anything?? or does anything look out of place? im a little worried.

I think im going to get a larger scale mechanical gauge to see where there press really sits after 100psi..

I previously had a rb25 pump with billet gears and was showing the same signs

any help would be HUUUUUGELY appreciated im really stumped and worried.

Cheers

Corey

Edited June 17, 2014 by ScreamerNewbie

[KiwiRS4T]

I see my earlier post is dated a year ago and everything seems ok despite oil pressures similar to yours. I'm using Motul 300V 10W 40

[ScreamerNewbie]

did you ever go lower viscosity? or didn't wana due to risk to the bearings?

[r33_racer]

If your bearings clearances are all standard then use a standard viscosity oil which I think is a 30 weight?

If you cant get the pressure to drop when warm below say 120psi at full noise where the oil relief is cracked open then you will need to reduce the spring pressure in the bypass of the pump. If you don't want to do that then you can hook up an external Peterson oil pressure regulator between your sandwich plate and oil cooler/filter arrangement and plumb that in so you can regulate the pressure going into the main oil gallery.

[KiwiRS4T]

did you ever go lower viscosity? or didn't wana due to risk to the bearings?

No because my RB30 is a stock block except for rings, bearings and conrod bolts

[pet vl]

And iam still haveing trouble any idears its my car looking i to changing the spring in the pump HELP

[KiwiRS4T]

On 10/15/2017 at 10:38 PM, pet vl said:

And iam still haveing trouble any idears its my car looking i to changing the spring in the pump HELP

Be more specific...what is your problem? What is the cold oil pressure and how long does it take to drop to say 100 psi?

I see your other post - just post in one place!

See what happens when you compare the spring pressures.